Liquid expansion power element



June 20, 1961 J. SlRl 2,989,083

LIQUID EXPANSION POWER ELEMENT Filed Nov. 2, 1959 2 Sheets-Sheet 1 1 INVENTOR. Law; J lR/.

June 20, 1961 L. J. SlRl 2,989,083

LIQUID EXPANSION POWER ELEMENT Filed Nov. 2, 1959 fin? 3Z7 PI 4 2 Sheets-Sheet 2 INVENTOR. Lou/.5 J. 5M1.

States Patent 3 Claims. (Cl. 137-788) This invention relates generally to power element or diaphragm assemblies, and particularly to power elements adapted for use with a liquid change and responding to thermal expansion of the liquid.

As is well known, actuator elements of the type herein disclosed are used extensively for actuation of switches or other control apparatus which have application in the regulation of pressure and temperature in air conditioning, refrigeration and allied fields. In my copending application Serial No. 790,463, filed February 2, 1959, titled Fluid Expansion Power Element, there is disclosed and claimed a power element of the type herein referred to. The present invention is embodied in a version of the power element described in said copending application which is particularly adapted to accommodate the relatively high internal pressures occurring when a solid charge or complete liquid fill is used in the power element and accompanying bulb and capillary tube. When this type of fill is used, any bulging deformation of the relatively thin diaphragm material because of the heavy internal pressure results in a change in the total volume of the liquid filled system. Any such permanent change in the volume of the system causes a highly undesirable loss of temperature setting and calibration of the control device in which the power element is incorporated.

It is an object of the present invention to provide a power assembly in which deformation of the diaphragm element cannot occur at the critical point which occurs as the element picks up the load of the switch linkage or other apparatus to be actuated.

A further object of the present invention is to provide a power element assembly in which the thrust pin or actuating pin is moved by displacement of a rigid plate with the flexible diaphragm component being supported or backed by a second rigid plate over the major portion of its area. I

The full nature of the invention will be understood from the accompanying drawings and the following description and claims:

FIG. 1 is a side sectional view taken generally along the line 11 of FIG. 2.

FIG. 2 is a plan view of the structure shown in FIG. 1.

FIG. 3 is a top plan view of a component of the structure shown in FIG. 1.

FIG. 4 is a top plan view of the diaphragm, capillary and bulb assembly.

Referring initially to FIGS. 1 and 2, there is shown at agenerally rectangular plate having upstanding ears 11 which are deformed to stake the plate 10' to a support plate 12. The plates 10 and 12 are provided with registering apertures 13 which may be utilized to mount the assembly.

The support plate 12 is provided with an annular arcuate portion 14 which bounds a central oifset portion 16. The portion of the plate 12 outboard of the arcuate area 1 4 is provided with an inclined configuration as indicated at 17.

Within the chamber bounded by the plates 10 and 12 there is disposed a rigid plate 18 having a circular configuration with an annular boss 19 extending from one face of the plate adjacent the marginal edge thereof. Closely overlying the plate is a relatively thin, flexible, metallic diaphragm 21 which extends across the pcripheral surface of the plate 18 and is rigidly secured to the rear face of plate 18 by solder or similar means, as indicated at 22. The plate 18 is formed to provide an integral pin 23 which is capped by a hardened pin adaptor 24. The pin adaptor extends freely through a central aperture 26 in the plate 10. A spider-type spring 27 (shown in detail in FIG. 3) engages one face of the plate 10 and the outwardly flanged portion 28 of the pin adaptor 24. The spring 27 thus serves to urge the assembly formed by plate 18 and diaphragm 21 against the adjacent surface of the plate 12.

The annular boss in the plate 18 is provided with an aperture which receives the end portion 29 of a capillary tube 31, the tube being soldered to the plate, as indicated at 32. As will be apparent from FIG. 4, the tube is provided with two concentric coils within the space bounded by the plates 10 and 12 and extends to a remote bulb 33. As may be seen in FIG. 2, the capillary tube extends through an aperture in the plate 12 and is fixed with relation thereto by means of solder as indicated at 34. It will be understood that the space between the diaphragm 21 and the plate 18, together with the bore of the capillary tube and the interior of the bulb 33, provides an enclosed chamber which accommodates a liquid having relatively high coeflicient of thermal expansion.

With the bulb 33 located in an enclosure whose temperature is to be sensed it will be evident that a variation in the temperature of the liquid in the bulb will result in a variation in the volume of the liquid contained in the closed system. Thus, upon an increase in temperature at the bulb 33, the consequent increase in volume of the liquid will cause the plate 18 to move away from the diaphragm, moving the pin 23 and consequently the pin adaptor 24 downwardly as viewed in FIG. 1. During this initial motion when the pin adaptor 24 is picking up the load, the arcuate portion 14 of the plate 12 will prevent any bulging of the diaphragm. Movement of the plate 18 beyond its initial stage because of increasing volume of the liquid will unroll the diaphragm away from the plate 12. During this portion of the movement, although the diaphragm is separated from the plate, since it is then under considerable tension, it cannot bulge outwardly. The arcuate portion of the plate 14 thus prevents bulging of the diaphragm 21 at the critical period when it is picking up the load placed on the adaptor pin 24. The power element of the present invention is thus capable of repeated operation without permanent deformation of the diaphragm component even under the relatively large unit pressures developed in solidly charged liquid fill systems.

While the invention has been disclosed and described in some detail in the drawings and foregoing description, they are to be considered as illustrative and not restrictive in character, as modifications may readily suggest themselves to persons skilled in this art and within the broad scope of the invention, reference being bad to the appended claims.

The invention claimed is:

1. A power element assembly adapted to accommodate a solid charge liquid fill comprising a rigid plate having a circular configuration and an annular boss extending from one face of said plate adjacent the marginal edge thereof, a flexible metallic diaphragm overlying said one face of said plate and sealed to the marginal portion of the opposite face of said plate, said diaphragm having a single circumferential corrugation therein contiguous with said annular boss, the central circular area of said diaphragm bounded by said corrugation closely overlying the central area of said plate, and a support plate closely overlying the face of said diaphragm remote from said plate, said support plate Patented June 20, 1961 having an annular arcuate portion accommodating said annular boss and diaphragm corrugation and having a central ofiset portion contiguous with said central area of said diaphragm, a spring yieldably urging said rigid platetoward said support plate, and. anaperture in said annular boss communicating with a remote liquid filled bulb and capillary tube assembly, whereby said rigid plateis moved relative to said support plate in response to increased liquid pressure.

2. A power element assembly. adapted to accommodate a solid charge liquid fill comprising, a rigid plate having a circular configuration and an annular boss extending from one face of saidplateadjacent themar.- ginal edge thereof, a flexible metallic diaphragm overlying'said one face of said plate and: sealedftosaid plate, said diaphragm having a single circumferential corrugation therein contiguous with saidannular, boss, the central circular area of said diaphragmbounded by said corrugation closely overlying the central area of: said plate, and a support plate closely overlying the face of said diaphragm remote from said plate, said support plate having an annular arcuate portion accommodating said annular boss and diaphragm corrugation and having a central oifset portion contiguous with said' central area of said diaphragm, a spring yieldably urging said rigid plate toward said support plate, and an aperture in said first mentioned plate communicating with a remote liquid filled bulb and capillary tube assembly, whereby said rigid plate is moved relative to said support plate in response to increased liquid pressure.

3. A power element assembly adapted to accommodate a solid chargeliquid fill comprising, a rigid plate having a circular configuration andfan; annularbossex and diaphragm corrugation, a spring, yieldably urging said rigid plate toward, said support plate, and an aperture in said first mentioned plate communicatingv with a remote filled bulb and capillary tube assembly, whereby said, rigid plate is moved rel'ativeto said support plate in response to increased liquid pressure.

References Cited'in the file of this patent UNITED STATES PATENTS Chilton May 6, 1941 Schroeder Jan, 31, 1950 

